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Date: Sat, 29 Aug 2020 17:43:58 -0700 From: Joe Perches <joe@...ches.com> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org> Cc: Kees Cook <keescook@...omium.org>, "Gustavo A . R . Silva" <gustavoars@...nel.org>, Denis Efremov <efremov@...ux.com>, Julia Lawall <julia.lawall@...ia.fr>, Alex Dewar <alex.dewar90@...il.com>, Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > Output defects can exist in sysfs content using sprintf and snprintf. > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > used for outputting sysfs content and it's possible to overrun the > PAGE_SIZE buffer length. > > Add a generic sysfs_emit function that knows that the size of the > temporary buffer and ensures that no overrun is done. > > Add a generic sysfs_emit_at function that can be used in multiple > call situations that also ensures that no overrun is done. This preliminary coccinelle script converts ~5000 instances treewide. There are still many remaining instances that could be converted. $ git grep -w sysfs_emit -- '*.[ch]'|wc -l 4702 $ git grep -w sysfs_emit_at -- '*.[ch]'|wc -l 229 $ cat sysfs_emit.cocci @@ identifier d_show =~ "^.*show.*$"; identifier arg1, arg2, arg3; @@ ssize_t d_show(struct device * - arg1 + dev , struct device_attribute * - arg2 + attr , char * - arg3 + buf ) { ... ( - arg1 + dev | - arg2 + attr | - arg3 + buf ) ... } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - sprintf(buf, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; expression chr; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - strcpy(buf, chr); + sysfs_emit(buf, chr); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - sprintf(buf, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... - len += scnprintf(buf + len, PAGE_SIZE - len, + len += sysfs_emit_at(buf, len, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; expression chr; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { - strcpy(buf, chr); - return strlen(buf); + return sysfs_emit(buf, chr); } @@ identifier k_show =~ "^.*show.*$"; identifier arg1, arg2, arg3; @@ ssize_t k_show(struct kobject * - arg1 + kobj , struct kobj_attribute * - arg2 + attr , char * - arg3 + buf ) { ... ( - arg1 + kobj | - arg2 + attr | - arg3 + buf ) ... } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - sprintf(buf, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; expression chr; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - strcpy(buf, chr); + sysfs_emit(buf, chr); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - sprintf(buf, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... - len += scnprintf(buf + len, PAGE_SIZE - len, + len += sysfs_emit_at(buf, len, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; expression chr; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { - strcpy(buf, chr); - return strlen(buf); + return sysfs_emit(buf, chr); }
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